This application claims the priority of Korean Patent Application No.: 2004-32198, filed on May 7, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to an apparatus for manufacturing a semiconductor device, and more particularly, to an inclination-angle measuring apparatus for an ion beam.
2. Description of the Related Art
Ion implantation is a technique for ionizing and accelerating impurities in a form of an ion beam and then implanting an appropriate amount of the ionized impurities into a desired region of a semiconductor substrate, material film or the like. Ion implantation is a part of the semiconductor fabrication procedure that selectively implants high-pure impurities into the substrate. In ion implantation, the position and the implantation depth of implanted ions can be precisely controlled and has an excellent characteristic of reappearance in comparison with a thermal diffusion process. U.S. Pat. Nos.: 5,343,047 and 5,641,969 disclose examples of ion implantation apparatuses.
However, as semiconductor devices have become more highly integrated and designed for higher performance levels, implanting ions requires more precise control. That is, the number, the implantation region and the implantation depth of the implanted ions need to be more strictly controlled in order to fabricate the semiconductor devices with higher integration and higher performance. In order to achieve this control, precise control of the inclination angle of an ion beam as well as the intensity of the ion beam is required.
If the inclination angle of the ion beam is imprecise, a channeling effect can be generated, and a shadow effect can be generated due to an upper mask pattern. Therefore, the inclination angle of the ion beam should be precisely measured to prevent the channeling effect and the shadow effect, and to precisely control the number, the implantation region and the implantation depth of the implanted ion.
In order to measure the inclination angle of the ion beam, ion implanting equipment generally includes an inclination-angle measuring apparatus. U.S. patent application publication No. 20030197132A1 published on Oct. 23, 2003 and entitled “Apparatus and method for measuring inclination angle of ion beam” by Keum et al. (the “Keum application”), which is commonly owned by an assignee of the present invention, discloses several examples of ion beam inclination-angle measuring apparatuses and a method for measuring an inclination angle of the ion beam using the same. The Keum application is hereby incorporated by reference in its entirety for all purposes as if fully set forth herein.
In the Keum application, FIG. 4 illustrates a schematic view of a construction of a spot ion beam inclination-angle measuring apparatus. Additionally, in the Keum application, FIG. 10 illustrates a schematic view of a construction of a ribbon ion beam inclination-angle measuring apparatus. In the Keum application, a Faraday cup assembly of an ion current measuring unit is rotated up and down and/or left and right, while ion current induced by the ion beam received in the Faraday cup assembly is measured. Additionally, a rotation angle of the Faraday cup assembly, at which the maximum ion current is generated, is calculated on the basis of the measured current and its variation. The inclination angle of the ion beam can be obtained from the calculated rotation angle of the Faraday cup assembly.
However, the Faraday cup assembly in the Keum application has a different structure for measuring a spot ion beam and for measuring a ribbon ion beam. The inclination-angle measuring apparatus for the spot ion beam cannot be used for measuring the inclination angle of the ribbon ion beam generated by the ion implantation equipment.
Further, the Faraday cup assembly measuring the inclination angle in the Keum application includes a single or plurality of Faraday cups formed of graphite. A hole in the Faraday cup that receives the ion beam is limited by its sidewall structure. If the sidewall structure is cast or molded using graphite to fabricate a Faraday cup, the hole have a size of several millimeters (mm). For example, even if it is not impossible, it is considerably difficult to limit the hole by the sidewall structure to a length (or diameter) smaller than 1 mm. If the hole of Faraday cup is large in size, the detection resolution of the inclination angle of the spot ion beam has a predetermined limitation. The limitation of the detection resolution becomes an obstacle in precisely controlling the inclination angle of the ion beam.
Additionally, since the ion beam is increased in size and accordingly, a Faraday cup and its dependent hole are concurrently increased in size, the detection resolution of the inclination angle becomes worse. For example, in a process where a 300 mm wafer is used, a larger ion beam is required to improve productivity. If an inclination-angle measuring apparatus has the same structure as a conventional inclination-angle measuring apparatus and is larger in size, the detection resolution of the inclination angle deteriorates.
Additionally, the Faraday cup assembly of the ribbon ion beam inclination-angle measuring apparatus disclosed in the Keum application is constructed as an assembly of a plurality of Faraday cups. The plurality of Faraday cups is fixedly disposed along a horizontal axis by a length of the ribbon ion beam. Accordingly, the Faraday cups adjacent to one another have a predetermined interval therebetween. The interval is twice as much as a sidewall thickness of the Faraday cup. Accordingly, the conventional inclination-angle measuring apparatus has a drawback in that the ribbon ion beam has a blind region between adjacent Faraday cups in which the inclination angle cannot be measured.